Jami and CJ -- some great links -- just the kind of thing I was looking for! And Ludi, I think a lot of us are in your situation -- so how to make the best of what we have? Leila -- good point. There are no 'one size fits all' solutions -- we need a variety of options that can be adapted to local materials, conditions, and legal requirements.
I've done a bit more digging and found more websites that might be of help:
is the home site for Village Building Convergence, a Portland, OR based organization whose goal is: "We will come together to create benches, community kiosks, gardens, street paintings, tile mosaics, and more! Come join your neighbors as they bring to life the natural building, permaculture, and public art projects that they’ve been planning. Learn valuable skills for urban sustainability and social regeneration while celebrating the creativity and diversity of our wonderful city!" They are involved in a straw clay retrofit
I'm thinking that earthbags might be a good retrofit option but I was not able to find anyone actually doing it.